Method for coating optical substrates with antireflective coatings that can be etched

摘要

The method belongs to the metal evaporation by deposits category in a reactive atmosphere in the chamber of a vacuum evaporator. It consists in placing in the chamber pre-cleaned substrates, evacuating the chamber by a conventional jusqur process to obtain a pressure of at most 1.5 μ Pa (10 ^-8 torr), injecting pure oxygen at a flow rate adjusted so that the pressure is between 2 and 4 m Pa to 3 Pa m (2 x 10 ^-5 torr). to expose a heated boat arranged in the chamber and containing chromium at a temperature such as a chromium oxide layer grows in thickness on the substrates from 0.1 to 0.5 nm per second, to 0.2 nm per second, and to hide the platform when the chromium oxide layer has reached a thickness corresponding to the first extinction in specular reflection at substantially normal incidence. The growth rate is controlled by the resonance derived from a quartz which is subjected to the repository. Extinction is controlled in white light at 3400 K on a substrate witness previously metallized.